The Iranian Revolutionary Guards have reportedly launched ground-to-ground mid-range ballistic missiles from the western Iranian provinces of Kermanshah and Kurdistan into the eastern Syrian province of Deir-ez Zor.

"The spilling of any innocent blood will not go unanswered," Press TV cited a statement by the Revolutionary Guards as saying.

The Revolutionary Guards targeted the bases and headquarters of terrorists that Iran believes to be responsible for the Tehran attacks. The missiles have reportedly killed large numbers of terrorists and inflicted significant material damage, Tasnim said.

A number of videos purporting to show the moment of the missile launch have emerged online.

The first video was taken in a western Iranian city by a man who seems to have spotted the missile launch.

"I bet that's a missile," a man in the video is heard saying.

The terrorists targeted the Iranian capital on June 7 in a twin attack, with four armed assailants attacking the country's parliament while a suicide bomber blew himself up at the Imam Khomeini Mausoleum. Islamic State (IS, formerly ISIS/ISIL) claimed responsibility for the attack, which killed 18 people and injured 50 more.